TENSILE TESTING AND THE MECHANICAL PROPERTIES OF MATERIALS

TENSILE TESTING AND THE MECHANICAL PROPERTIES OF MATERIALS





Abstract

Tensile testing is one of the most important techniques that are used for the testing different engineering materials and metals. It has a great significance in the field of metallurgical engineering. In this paper we will discuss that what tensile strength is. How to test a material's tensile strength and which equipments are used for it. The tensile properties of the materials will be analyzed along with their relationship with the mechanical behavior and structures. This paper aims to make the readers capable of selecting appropriate metal according to their requirements.

Introduction

There are many reasons to perform tensile testing of the materials. The decision of selecting an appropriate material is based on the results that are obtained from the tensile testing for a particular engineering application. The results generally include specification of the material for the purpose of quality assurance. Tensile properties are often measured during the making of a new material and the corresponding processes that are involved in it. For the purpose of predicting the behavior of a material tensile properties are of crucial importance. A material is tested under different loading conditions which are different from uniaxial tension. The primary concerns for the metallurgist when developing a new material is the tensile strength.

The strength is usually measured in terms of maximum stress up to which a material can with stand or the minimum stress that can cause significant plastic deformation. These measured strengths are taking as the maximum limit up to which the material can bear force in a frame of an engineering structure. The strength of material is also measured in terms of ductility which is defined as the measure of deformation of material before fractures. However, ductility is often not considered in design specifications. Instead ductility is taken in to consideration for the assurance of toughness and quality of the material. Elastic properties are also measured during tensile testing but special procedures and techniques are used. For the precise and accurate measurements of elastic properties ultrasonic techniques are used (ASMI publications, 2012, Introduction to tensile testing, chapter 1, p.1).

Testing Procedures and Equipments

H10-50KT/S Universal testing dual column machine is used for testing the tensile strength of the material whose image and specifications are as under

(SOURCE: SDATLAS.com, 2005)

Graph of Stress and strain see Appendix for tabular data

Elastic Modulus

It is defined as the tendency of an element to deform elastically. From the graph the elastic modulus is found to be 68.

Yield Stress

Yield stress is defined as the level of stress at which a material starts to behave elastically. From the graph of stress versus strain the yield stress is found to be 124 Pa.

Tensile strength

The tensile strength, sTS, of a material is the maximum stress it can withstand and is typically measured in MPa (the tensile strength is sometimes indicted as the ultimate tensile strength and given the abbreviation UTS). It is calculated by:

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